The present invention relates to a method of controlling the weight of granulated (delayed-action) products on a machine for metering such products into containers.
The present invention also relates to a metering machine implementing the above method.
The method according to the present invention may be used to an advantage on metering machines for metering a number of granulated products into hard-gel capsules, to which the following description refers purely by way of example.
As is known, one of the biggest problems on such machines is controlling the weight of the dosage of each product.
One solution currently adopted on multiple metering machines for successively metering a number of different products into one capsule consists in removing from the machine and weighing a specimen capsule of known tare into which only one of the products involved in the metering process has been dispensed.
The above solution involves several drawbacks. In particular, the various granulated products are weighed with the machine idle, which, as each single product and each single metering member must be controlled, therefore results in considerable downtime. Moreover, all the above operations must be repeated for each change in the metered products, for each variation in the amount of product to be metered, and at any rate at predetermined intervals to compensate for any variation in the parameters, on or off the machine, affecting the metering cycle. In addition to the complex nature and the time required to perform the weighing operations, the possibility also exists of a container subjected to the above operations, and therefore containing only one product, being mistaken for and packed with those containing all the metered products.
A second solution enabling control during normal operation of two-product metering machines involves two weighing methods: a first for controlling the weight of the first product, which, after it is metered out, and before metering out the second product, is removed from the capsule by opening the bottom of the capsule and collecting the product which falls out by force of gravity, and is sent to a weighing station; and a second for controlling the weight of the second product, which is calculated by subtracting from the weight of a capsule of known tare, and containing both products, the tare of the capsule and the weight of the first product.
A major drawback of this second solution is that it is limited to machines metering at most two different products. Moreover, when the capsule is opened to extract the first product, fragments of the capsule may also be collected together with the product, thus seriously impairing the accuracy of the weighing operation.